This common lawn mushroom frequently comes up after rains in early summer (or nearly year-round in warmer areas), and is also found in pastures and meadows. It has a thin cap, a skinny stem, and a medium brown spore print. Several features of Agrocybe pediades are fairly variable, including its colors and the size of its spores. It is often treated as a species "cluster" in field guides, but recent investigators have been leaning toward defining it as a single, variable species. Agrocybe semiorbicularis, once separated from Agrocybe pediades on the basis of its slightly larger spores and thinly sticky cap, has now been synonymized.

Agrocybe pediades has a partial veil, but it is so ephemeral that you will need to be looking at buttons the size of pencil erasers to see it. Within a few hours, all evidence of the veil has usually disappeared. Collections I have made in California, Colorado, and Illinois have demonstrated a color change to red or pink when a drop of KOH is applied to the cap surface; other Agrocybe species I have tested show no color change or a change to dull yellow.

Description:

Ecology: Saprobic; growing alone or gregariously in lawns, meadows, and other grassy areas (and sometimes on wood chips, dung, or sand); summer (but nearly year-round in warm climates); common and widely distributed in North America.

Gills: Attached to the stem; pale grayish brown becoming brown to rusty or cinnamon brown in maturity; close or, in my experience, often nearly distant; when young covered by an ephemeral white partial veil.